The present invention relates to a double-seal/oil-reservoir system for a motor/pump assembly for sealing the drive shaft of a shaft-driven pump from undesired leakage, and, more particularly, shaft-sealing arrangements for sealing the drive shafts of pumps used in whirlpool tub and spa installations.
Whirlpool bath and spa-type installations typically include a tub structure having a plurality of water jets for introducing a pressurized stream of water and air into the tub and a suction inlet from which water is withdrawn. The water withdrawn from the tub through the suction inlet is provided to a shaft-driven recirculation pump which pressurizes the water and distributes the pressurized water to the water jets for re-introduction into the tub.
The recirculation pump typically includes a motor driving an impeller-type centrifugal pump through a connecting drive shaft. The impeller is rotated about an axis in a pump housing that includes an inlet side and an outlet side separated by an internal partition that defines a scroll-like impeller chamber. Water drawn into the inlet side of the impeller chamber is pressurized by the rotating impeller and forced to and through the outlet.
The motor shaft typically passes through an end housing of the pump and is supported for rotation by a journal-type bearing. In general, the journal bearing is adequate to provide a long, trouble-free operating life while also providing reasonably effective control of leakage from the interior of the pump to the exterior via the clearance between the outside diameter of the shaft and the inside diameter of its journal bearing. While the shaft/journal system is effective to control leakage, some of the water passing through the pump will xe2x80x9cweepxe2x80x9d to the exterior of the pump. The weepage rate can vary between, for example, 1-drop/hour to 1-drop/minute of operation of the pump.
The user of the whirlpool tub or spa will commonly use various soaps, detergents, body lotions, and the like that go into solution in the circulating water. Additionally, is not uncommon to pre-treat the water with various materials including anti-bacterial, anti-fungal, pH-control chemicals, colorants, ozone, bromine and/or chlorine-release chemicals that also go into solution in the circulating water. The nature of some of these solutes is such that they can aggressively degrade a shaft seal. As a consequence, the weepage about the drive shaft, when it evaporates, will deposit various solids from the water solution, and, additionally, chemical activity can degrade the seal-function until the pump must be replaced or otherwise serviced. In practice, seal integrity is one of the primary factors limiting the operational life of motor/pump assemblies in the spa and whirlpool tub market.
In view of the above, it is an object of the present invention, among others, to provide an effective and low-cost double-seal/oil-reservoir system for a motor/pump assembly as a solution to the seal-integrity problem associated with shaft-driven pumps, particularly in whirlpool tub and spa installations.
In view of these objects, and others, the present invention provides a double-seal/oil-reservoir system for use in pumps used in the whirlpool tub and spa industry. The system includes first and second mechanical seals spaced apart on the operating shaft to define a volume or space therebetween that contains a volume of oil or oil-like fluid. The oil or oil-like fluid assists in maintaining the integrity of the first and the second seals while greatly limiting the opportunity for any leakage or seepage of the circulating water. In the preferred embodiment, the first and second seals are annular carbon ring/ceramic ring axial face seals. The carbon ring includes an axial face that is resiliently biased against a cooperating axial face of the ceramic seal to form a fluid-tight seal therebetween. While cooperating carbon/ceramic axial-face seals are preferred, conventional elastomeric xe2x80x98lipxe2x80x99 seals can also function as either and/or the first and second seals.
The combination of the first and the second seals axially spaced on the operating shaft and the intermediate volume or chamber containing an oil or oil-like fluid greatly reduces the probability of leakage to the exterior of the pump housing and increases the operating life of the motor/pump assembly.
The present invention advantageously provides a double-seal/oil-reservoir system for containing seepage from the pump that solves the prior seal integrity problem.